There is increasing interest in Ocean Thermal Energy Conversion (OTEC) as a renewable source of electrical energy. OTEC uses the ocean's natural thermal gradient to generate power. In geographical areas with warm surface water and cold deep water, the temperature difference can be leveraged to drive a steam cycle that turns a turbine and produces power. Warm surface sea water passes through a heat exchanger, vaporizing a low boiling point working fluid to drive a turbine generator, thereby producing electricity. Unfortunately, one challenge with OTEC is the need for a cold water pipe (CWP) that must be capable of drawing large volumes of water from deep in the ocean up to the surface.
The CWPs used in OTEC are often large diameter pipes that are 4 meters (m) or more in diameter and over 1000 m in length. CWPs are often built in situ by coupling smaller segments of pipe together to form a CWP of a desired length. A CWP must be able to withstand various environmental forces, including wave-induced motion (WIM) cyclic strain, WIM axial buckling, vortex-induced vibration (VIV) cyclic strain, platform rotation, clump weight axial forces, and the like. Also, due to the always present threat of unpredictable and extreme weather in deep water environments, the CWPs are engineered so that they can withstand forces induced by severe storms during fabrication, assembly, and deployment of the CWP. Typically, these induced forces on the CWP are less after the CWP is installed into the ocean. CWPs are often made of fiberglass and/or carbon-fiber composites to meet the various forces that they will, or might, encounter during installation and/or operation. Such CWPs are expensive, and they are time-consuming to build and install. For example, it can take 90 days or more to build and install such a CWP. Because extreme weather events have been shown to induce greater forces into the CWP structure during fabrication, these long deployment times increase the likelihood that a CWP will encounter and must withstand an extreme weather event.